Causes and differential diagnosis

The pathophysiology of CPP is often multifactorial with significant physical, psychological, and social components. Box 44.1 shows the differential diagnosis for CPP.

Gynaecological causes

Endometriosis

Endometriosis is the presence of endometrial-like tissue outside the uterus, which induces a chronic inflammatory reaction.

Pelvic inflammatory disease

Pelvic inflammatory disease results from ascending infection from the endocervix and vagina into the uterus, tubes, and surrounding structures. The inflammation may cause adhesions leading to CPP, damage to tubal epithelium leading to increased chance of ectopic pregnancy, and infertility. Approximately 85% of cases are acquired via sexual activity, while the remaining 15% of cases are iatrogenic and may occur after invasive procedures such as endometrial bi­opsies, uterine curettages, or insertion of intrauterine contracep­tive devices. Primary pathogens include Neisseria gonorrhoea and Chlamydia trachomatis and up to 40% ofwomen may have coexisting infections. Secondary pathogens include Gardnerella vaginalis, Mycoplasma, and other aerobic and anaerobic organisms (6). Patients should also be screened for other sexually transmitted dis­eases and their sexual partners should also be screened and treated as appropriate. The triad of lower abdominal pain, adnexal tender­ness, and tender cervical excitation usually suggests acute pelvic in­flammatory disease. Prompt diagnosis and treatment is important as delay in management for a few days may increase morbidity.

Adhesions

Adhesions refer to abnormal attachments between two structures due to the presence of fibrous tissue. Pelvic adhesions are adhe­sions within the pelvic cavity, which may be produced following previous surgery, pelvic inflammatory disease, endometriosis, pre­vious radiotherapy, peritoneal dialysis, or intra-abdominal abscess. Adhesions do not always cause pain but are more likely to do so if they are dense and vascular, if they involve pain-sensitive structures such as the ovary or parietal peritoneum, or if they restrict mobility. The pain may be more pronounced when certain movement causes stretching of the adhesion tissue, pulling on the tissues attached to it (7, 8).

Adenomyosis

Adenomyosis is defined as the presence of heterotopic endometrial glands and stroma in the myometrium with adj acent smooth muscle hyperplasia. It affects approximately 1% of women and is often found

Box 44.1 Differential diagnosis for chronic pelvic pain

Gynaecological conditions

• Endometriosis

• Adhesions

• Pelvic inflammatory disease

• Chronic endometritis

• Ovarian cysts

• Ovarian remnant syndrome

• Pelvic congestion syndrome

• Residual ovarian syndrome

• Uterine fibroids

• Vulvodynia

• Vestibulitis

• Adenomyosis

• Cervical stenosis

Urological conditions

• Chronic urinary tract infections

• Interstitial cystitis

• Urolithiasis

• Bladder carcinoma

Gastrointestinal conditions

• Constipation

• Hernias

• Inflammatory bowel disease

• Irritable bowel syndrome

Musculoskeletal conditions

• Nerve entrapment syndrome

• Myofascial pain

• Pelvic floor myalgia

• Surgical scarring

Psychological conditions

• Anxiety

• Depression

• Personality disorders

• Physical/sexual abuse

• Stress

in multiparous women during their late 40s. Apart from pelvic pain, adenomyosis may produce dysmenorrhea, menorrhagia, and dyspareunia. Clinical examination often reveals a tender uterus.

Pelvic congestion syndrome

This is a syndrome characterized by the presence of pelvic pain as­sociated with pelvic varicosities and pelvic venous congestion with delayed emptying of the pelvic veins. The pain may be unilateral or bilateral; if it is unilateral it is more often situated in the left iliac fossa than the right as pelvic varicosities are more likely to occur in the left side. The pain is often described as a dull ache or a sensation of heaviness in the pelvic area. It is often exacerbated by menstruation, coitus, or prolonged standing (10).

Ovarian remnant syndrome

Ovarian remnant syndrome refers to the presence of functional ovarian tissue after unilateral or bilateral oophorectomy. It is often associated with severe endometriosis and pelvic adhesions, leading to inadvertent incomplete removal of the ovaries during oophorec­tomy. The absence of vasomotor symptoms in women not on hor­monal replacement therapy (HRT) or the presence of cyclical pain after bilateral oophorectomies should raise suspicion of this condi­tion. Symptoms can occur a few months to several years after sur­gery (11). Blood test often reveals follicle-stimulating hormone and oestradiol levels in the premenopausal range despite bilateral oo­phorectomies. Removal of ovarian remnants may lead to resolution of the CPP in 80% of cases as shown in a cohort study (12).

Residual ovarian syndrome or ovarian retention syndrome

Residual ovarian syndrome or ovarian retention syndrome is char­acterized by the presence of recurrent or intermittent pelvic pain or dyspareunia after hysterectomy with conservation of ovaries. The pain is often due to a combination of development of functional cysts in an ovary involved in adhesion. The pain is often cyclical or intermittent in nature and again can occur a few months to several years after the hysterectomy.

Non-gynaecological causes

Interstitial cystitis and painful bladder syndrome

Different centres and units have different definitions for the term ‘interstitial cystitis’. The International Continence Society suggests that ‘painful bladder syndrome’ may be a better name to describe ‘a condition of suprapubic pain related to bladder filling, accompanied by other symptom such as increased day time and night time fre­quency in the absence of proven urinary tract infection or other ob­vious pathology’. On the other hand, ‘interstitial cystitis’ is best used to describe a ‘painful bladder syndrome with typical cystoscopic and histological features’. The symptoms often last for more than 6 weeks (13). The exact aetiology of interstitial cystitis or painful bladder syndrome is not known and may be multifactorial.

Irritable bowel syndrome

This is a common gastrointestinal disorder characterized by a chronic, relapsing pattern of lower pelvic pain associating with alteration of bowel function including constipation or diarrhoea. It is defined by the Rome III criteria (available at https://www.theromefoundation. org/assets/pdf/19_RomeIII_apA_885-898.pdf) with recurrent ab­dominal pain, discomfort for at least 3 days per month in the last 3 months, with a symptom onset at least 6 months prior to diagnosis and associated with two or more of the following: (a) improvement with defecation, (b) onset associated with a change in frequency of stool, or (c) onset associated with a change in form or appearance of stool. The use of a symptom- screening questionnaire may be helpful. The onset is usually during late adolescence to early adulthood and seldom occurs in later life.

Musculoskeletal

It is not uncommon for musculoskeletal conditions to present as CPP. Many musculoskeletal structures of the back and lower limbs share segmental innervation with urogenital structures and may cause referred pain over the lower abdomen and pelvic floor mim­icking pelvic pain (14).

Psychosocial factors

Psychosocial factors play an important role in CPP. A patient's per­sonality, psychiatric illness, and coping skills all affect how she per­ceives the pain and responds to the treatment. Depression may be a cause or a consequence of the CPP. A previous history of sexual or physical abuse and unpleasant life experiences or life stressors is as­sociated with a higher incidence of CPP (17).